Reconfiguring processing groups for cascading data workloads

ABSTRACT

Reconfiguring processing groups for cascading data workloads including receiving a request to reconfigure a computing system to execute a workload, wherein the computing system comprises a first processing group and a second processing group, wherein the first processing group comprises a first central processing unit (CPU), a first graphics processing unit (GPU), and a second GPU, and wherein the second processing group comprises a second CPU and a third GPU; reconfiguring the computing system including activating a processor link spanning the first processor group and the second processor group between the second GPU and the third GPU; and executing the workload using the first GPU, second GPU, and third GPU including cascading data, via processor links, from the first CPU to the first GPU, from the first GPU to the second GPU, and from the second GPU to the third GPU.

BACKGROUND Field of the Invention

The field of the invention is data processing, or, more specifically,methods, apparatus, and products for reconfiguring processing groups forcascading data workloads.

Description Of Related Art

The development of the EDVAC computer system of 1948 is often cited asthe beginning of the computer era. Since that time, computer systemshave evolved into extremely complicated devices. Today's computers aremuch more sophisticated than early systems such as the EDVAC. Computersystems typically include a combination of hardware and softwarecomponents, application programs, operating systems, processors, buses,memory, input/output devices, and so on. As advances in semiconductorprocessing and computer architecture push the performance of thecomputer higher and higher, more sophisticated computer software hasevolved to take advantage of the higher performance of the hardware,resulting in computer systems today that are much more powerful thanjust a few years ago.

SUMMARY

Methods, systems, and apparatus for reconfiguring processing groups forcascading data workloads are disclosed in this specification.Reconfiguring processing groups for cascading data workloads includesreceiving a request to reconfigure a computing system to execute aworkload, wherein the computing system comprises a first processinggroup and a second processing group, wherein the first processing groupcomprises a first central processing unit (CPU), a first graphicsprocessing unit (GPU), and a second GPU, and wherein the secondprocessing group comprises a second CPU and a third GPU; reconfiguringthe computing system including deactivating a processor link between thefirst CPU and the second GPU, deactivating a processor link between thesecond CPU and the third GPU, and activating a processor link spanningthe first processor group and the second processor group between thesecond GPU and the third GPU; and executing the workload using the firstGPU, second GPU, and third GPU including cascading data, via processorlinks, from the first CPU to the first GPU, from the first GPU to thesecond GPU, and from the second GPU to the third GPU.

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescriptions of exemplary embodiments of the invention as illustrated inthe accompanying drawings wherein like reference numbers generallyrepresent like parts of exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 sets forth a block diagram of an example system configured forreconfiguring processing groups for cascading data workloads accordingto embodiments of the present invention.

FIG. 2 sets forth a block diagram of an example system configured forreconfiguring processing groups for cascading data workloads accordingto embodiments of the present invention.

FIG. 3 sets forth a block diagram of an example system configured forreconfiguring processing groups for cascading data workloads accordingto embodiments of the present invention.

FIG. 4 sets forth a flow chart illustrating an exemplary method forreconfiguring processing groups for cascading data workloads accordingto embodiments of the present invention.

FIG. 5 sets forth a flow chart illustrating an exemplary method forreconfiguring processing groups for cascading data workloads accordingto embodiments of the present invention.

FIG. 6 sets forth a flow chart illustrating an exemplary method forreconfiguring processing groups for cascading data workloads accordingto embodiments of the present invention.

FIG. 7 sets forth a flow chart illustrating an exemplary method forreconfiguring processing groups for cascading data workloads accordingto embodiments of the present invention.

DETAILED DESCRIPTION

Exemplary methods, apparatus, and products for reconfiguring processinggroups for cascading data workloads in accordance with the presentinvention are described with reference to the accompanying drawings,beginning with FIG. 1. FIG. 1 sets forth a block diagram of automatedcomputing machinery comprising an exemplary computing system (152)configured for reconfiguring processing groups for cascading dataworkloads according to embodiments of the present invention. Thecomputing system (152) of FIG. 1 includes at least one processing group(190). The processing group (190) includes at least one computerprocessor or central processing unit (CPU) (156) as well as randomaccess memory (168) ('RAM') which is connected through a high speedmemory bus (166) and bus adapter (158) to CPU (156) and to othercomponents of the processing group (190). The processing group (190)also includes multiple graphics processing units (GPUs) (GPU A (194A),GPU B (194B)) coupled to the CPU (156) via processor links (196).

Stored in RAM (168) is an operating system (154). Operating systemsuseful in computers configured for reconfiguring processing groups forcascading data workloads according to embodiments of the presentinvention include UNIX, Linux™, Microsoft Windows™, AIX™, IBM's i OS™,and others as will occur to those of skill in the art. The operatingsystem (154) in the example of FIG. 1 is shown in RAM (168), but manycomponents of such software typically are stored in non-volatile memoryalso, such as, for example, on a disk drive (170). Also stored in RAM isa reconfiguration module (192), a module for reconfiguring processinggroups for cascading data workloads according to embodiments of thepresent invention.

The processing group (190) of FIG. 1 includes disk drive adapter (172)coupled through expansion bus (160) and bus adapter (158) to CPU (156)and other components of processing group (190). Disk drive adapter (172)connects non-volatile data storage to the processing group (190) in theform of data storage (170). Disk drive adapters useful in computersconfigured for reconfiguring processing groups for cascading dataworkloads according to embodiments of the present invention includeIntegrated Drive Electronics (‘IDE’) adapters, Small Computer SystemInterface (‘SCSI’) adapters, and others as will occur to those of skillin the art. Non-volatile computer memory also may be implemented for asan optical disk drive, electrically erasable programmable read-onlymemory (so-called ‘EEPROM’ or ‘Flash’ memory), RAM drives, and so on, aswill occur to those of skill in the art.

The example processing group (190) of FIG. 1 includes one or moreinput/output (‘I/O’) adapters (178). I/O adapters implementuser-oriented input/output through, for example, software drivers andcomputer hardware for controlling output to display devices such ascomputer display screens, as well as user input from user input devices(181) such as keyboards and mice. The example processing group (190) ofFIG. 1 includes a video adapter (209), which is an example of an I/Oadapter specially designed for graphic output to a display device (180)such as a display screen or computer monitor. Video adapter (209) isconnected to CPU (156) through a high speed video bus (164), bus adapter(158), and the front side bus (162), which is also a high speed bus.

The example processing group (190) of FIG. 1 includes a communicationsadapter (167) for data communications with other computers and for datacommunications with a data communications network. Such datacommunications may be carried out serially through RS-232 connections,through external buses such as a Universal Serial Bus (‘USB’), throughdata communications networks such as IP data communications networks,and in other ways as will occur to those of skill in the art.Communications adapters implement the hardware level of datacommunications through which one computer sends data communications toanother computer, directly or through a data communications network.Examples of communications adapters useful in computers configured forreconfiguring processing groups for cascading data workloads accordingto embodiments of the present invention include modems for wired dial-upcommunications, Ethernet (IEEE 802.3) adapters for wired datacommunications, and 802.11 adapters for wireless data communications.

FIG. 2 shows an exemplary system for reconfiguring processing groups forcascading data workloads according to embodiments of the presentinvention. As shown in FIG. 2, the exemplary system includes processinggroup A (190A) and processing group B (190B). Processing group A (190A)includes CPU A (156A), GPU A (194A), and GPU B (194B). CPU A (156A) iscoupled to GPU A (194A) via processor link A (196A). CPU A (156A) iscoupled to GPU B (194B) via processor link B (196B). Finally, GPU A(194A) is coupled to GPU B (194B) via processor link C (196C). Theexemplary system of FIG. 2 depicts two GPUs directly accessible by eachCPU in each processing group, and two processing groups on the system,each with one CPU. However, there need not be a restriction on thenumber of GPUs available within a processing group or the number ofprocessing groups on a system. The number of processing groups on thesystem may be determined, for example, by the number of CPU socketspresent.

Processing group B (190B) includes CPU B (156B), GPU C (194C), and GPU D(194D). CPU B (156B) is coupled to GPU C (194C) via processor link D(196D). CPU B (156B) is coupled to GPU D (194D) via processor link E(196E). Finally, GPU C (194C) is coupled to GPU D (194D) via processorlink F (196F).

As shown in the exemplary system of FIG. 2, processing group A (190A) iscoupled to processing group B (190B) via two communication paths. CPU A(156A) is coupled to CPU B (156B) via the intergroup fabric bus (202).Also, GPU B (194B) is coupled to GPU C (194C) via the inactiveintergroup processor link (204).

The processing groups (processing group A (190A), processing group B(190B)) are collections of computing elements on a system. Eachprocessing group may be assigned all of a workload or part of a singleworkload that is executed on multiple processing groups. The processinggroups communicate with one another, in part, using the intergroupfabric bus (202) between CPUs on each processing group.

The CPUs (CPU A (156A), CPU B (156B)) are processing units that managethe execution of a workload or part of a workload. The GPUs (GPU A(194A), GPU B (194B), GPU C (194C), GPU D (194D)) are accelerators thataid the CPUs in executing workloads. The GPUs may handle a variety ofdata processing tasks, including process non-graphic tasks, such asaudio or mathematical computations.

The processor links (processor link A (196A), processor link B (196B),processor link C (196C), processor link D (196D), processor link E(196E), processor link F (196F), intergroup processor link (204)) arehigh speed interconnects configured to transmit data between a CPU and aGPU or between two GPUs. The processor links may transmit data directlybetween a CPU and a GPU or between two GPUs, in that there exists nointermediary switch or other computing element on the processor linkbetween the CPU and the GPU or between the two GPUs. Each processor linkmay also be distinct from switching fabrics in that each processor linkmay include exactly two endpoints. The processor links are notperipheral component interconnects. The processor links may be NVlink™interconnects.

The intergroup processor link (204) differs from the other processorlinks (processor link A (196A), processor link B (196B), processor linkC (196C), processor link D (196D), processor link E (196E), processorlink F (196F)) in that the intergroup processor link (204) is aprocessor link spanning two processing groups (processing group A(190A), processing group B (190B)). The intergroup processor link (204)may be otherwise indistinguishable from the other processor links(processor link A (196A), processor link B (196B), processor link C(196C), processor link D (196D), processor link E (196E), processor linkF (196F)).

Each CPU (CPU A (156A), CPU B (156B)) may be limited in the number ofGPUs to which the CPU is able to connect via a processor link. Forexample, each CPU may be limited to connecting to no more than two GPUs.Similarly, each GPU (GPU A (194A), GPU B (194B), GPU C (194C), GPU D(194D)) may be limited in the number of CPUs and/or GPUs to which theGPU is able to connect via a processor link. For example, each GPU maybe limited to connecting to either one CPU and one GPU, or two GPUs.

The intergroup fabric bus (202) is a communications bus between two CPUswithin different processing groups. The intergroup fabric bus (202) maydirectly couple two CPUs such that no intermediary switch or othercomputing element exits between the CPUs. The intergroup fabric bus(202) is not a processor link and is not a peripheral componentinterconnect.

The exemplary system of FIG. 2 depicts the intergroup processer link(204) as inactive. A workload may be executed on the exemplary system ofFIG. 2, as shown, using both processing groups (processing group A(190A), processing group B (190B)). However, data processed by one GPUon one processing group is unable to be sent directly to another GPU ona different processing group. Rather, the data is sent from the GPU tothe CPU (via DMA to memory) within the same processing group, then sentfrom the CPU within the same processing group to the CPU within thetarget processing group via an intergroup fabric bus, and finally sentfrom the CPU within the target processing group to the target GPU.

For example, assume that data on GPU B (194B) is to be sent to GPU C(194C). The data sent from GPU B (194B) on the processing group A (190A)would be sent from GPU B (194B) to CPU A (156A), then from CPU A (156A)along the intergroup fabric bus (202) to CPU B (156B), and finally fromCPU B (156B) to GPU C (194C).

The exemplary system shown in FIG. 2 may be the default systemconfiguration. Specifically, the exemplary system shown in FIG. 2 may bethe configuration to which alterations are made in order to effectivelyexecute workloads requiring or benefiting from a reconfiguration of thedefault system shown in FIG. 2.

FIG. 3 shows an exemplary system for reconfiguring processing groups forcascading data workloads according to embodiments of the presentinvention. FIG. 3 shows a reconfiguration of the system depicted in FIG.2. Specifically, processor link B (196B) and processor link D (196D)have been deactivated, and the intergroup processor link (204) has beenactivated. In the exemplary system of FIG. 3, GPU B (194B) and GPU C(194C) are directly coupled to one another via the intergroup processorlink (204) and may exchange data bypassing the CPUs and the intergroupfabric bus (202).

A processor link is activated by transitioning the processor link from adeactivated or disconnected state to an activated or connected state. Inan active state, each CPU or GPU coupled to the active processor linkmay use the active processor link to transmit and receive data fromanother CPU or GPU coupled to the active processor link. A processorlink is deactivated by transitioning the processor link from anactivated or connected state to an inactivated or disconnected state. Inan inactive state, the inactive processor link is unavailable for use totransmit or receive data between the GPUs coupled to the processor linkor between the CPU and GPU coupled to the processor link.

Processor links (processor link A (196A), processor link B (196B),processor link C (196C), processor link D (196D), processor link E(196E), processor link F (196F)) may be activated or deactivated using abus multiplexer. A bus multiplexer is a device that selects one ofseveral input signals and forwards the input signal to an output line.For example, in order to deactivate processor link B (196) and activatethe intergroup processor link (204), a bus multiplexer may deselect theinput signal from CPU A (190A) to GPU B (194B) and select the inputsignal from GPU C (194C) to GPU B (194B). The example system of FIGS. 2and 3 may include multiple bus multiplexers. The bus multiplexer may becontrolled via signals received from a reconfiguration module.Activating the bus multiplexer may provide a static setup performed onceat the system boot time. The bus multiplexer may be unable to beactivated while the system is running (i.e., during runtime).

For further explanation, FIG. 4 sets forth a flow chart illustrating anexemplary method for reconfiguring processing groups for cascading dataworkloads according to embodiments of the present invention thatincludes receiving (402) a request (420) to reconfigure a computingsystem to execute a workload (422), wherein the computing systemcomprises a first processing group and a second processing group,wherein the first processing group comprises a first central processingunit (CPU), a first graphics processing unit (GPU), and a second GPU,and wherein the second processing group comprises a second CPU and athird GPU. Receiving (402) a request (420) to reconfigure a computingsystem to execute a workload (422), wherein the computing systemcomprises a first processing group and a second processing group,wherein the first processing group comprises a first central processingunit (CPU), a first graphics processing unit (GPU), and a second GPU,and wherein the second processing group comprises a second CPU and athird GPU may be carried out by a user instructing a reconfigurationmodule to reconfigure the system.

The received request may include a specific configuration desired by theuser to execute the workload. Alternatively, the received request mayinclude only a type of workload intending to be executed. Thereconfiguration module may determine, based on the type of workload, aparticular configuration that matches or suits the type or workloadreceived in the request. For example, the request (420) may indicatethat a user intends to execute a deep learning workload. Thereconfiguration module may determine that deep learning workloadsperform more efficiently using a GPU configuration allowing for data tobe cascaded between GPUs. The reconfiguration module may retrieve aconfiguration model corresponding to deep learning workloads from aconfiguration model repository and prepare to reconfigure the systembased on the configuration model.

The method of FIG. 4 further includes reconfiguring (404) the computingsystem including deactivating a processor link between the first CPU andthe second GPU, deactivating a processor link between the second CPU andthe third GPU, and activating a processor link spanning the firstprocessor group and the second processor group between the second GPUand the third GPU. Reconfiguring (404) the computing system includingdeactivating a processor link between the first CPU and the second GPU,deactivating a processor link between the second CPU and the third GPU,and activating a processor link spanning the first processor group andthe second processor group between the second GPU and the third GPU maybe carried out by a reconfiguration module sending signals to elementswithin the computing system to activate or deactivate specific processorlinks.

The computing system may be reconfigured based on the characteristics ofthe workload. For example, the reconfiguration module may access theworkload and evaluate the content of the workload. Based on theevaluation, the reconfiguration module may select a correspondingconfiguration to execute the workload.

The computing system may be reconfigured at boot time. Specifically, thereconfiguration may be performed as part of the setup process for thecomputing system. Reconfiguring the computing system at boot time mayinclude reconfiguring the computing system before the execution of theworkload initiates.

Steps 402 and 404 may be performed by, or primarily by, areconfiguration module. The reconfiguration module is software,hardware, or an aggregation of software and hardware that receives therequest to reconfigure and initiates the reconfiguration process. Thereconfiguration module may also evaluate the intended workload andworkload characteristics and select a corresponding configuration modelto execute the workload based on the workload characteristics.

The method of FIG. 4 further includes executing (406) the workload (422)using the first GPU, second GPU, and third GPU including cascading data,via processor links, from the first CPU to the first GPU, from the firstGPU to the second GPU, and from the second GPU to the third GPU.Executing (406) the workload (422) using the first GPU, second GPU, andthird GPU including cascading data, via processor links, from the firstCPU to the first GPU, from the first GPU to the second GPU, and from thesecond GPU to the third GPU may be carried out by utilizing thepreviously activated processor links to execute the workload. Cascadingdata refers to receiving data from one processing unit, such as a CPU orGPU, processing or manipulating the received data, and subsequentlyproviding the processed data to a different processing unit, such as aGPU.

For example, for a deep learning workload, one image may be providedfrom a CPU to a first GPU. The first GPU may compute certaincharacteristics of the image, such as gradients and solver optimization.The image and computations may then be sent from the first GPU to asecond GPU to verify the computations for the image. The image andcomputations may then be sent from the second GPU to a third GPU tofurther verify the computations for the image or to resolveinconsistencies in the computations. The process of sending data outfrom a CPU may be referred to as forward propagation. The image andcomputational results may then be sent back up to the CPU from the thirdGPU and through the second GPU and first GPU. The process of sendingdata toward a CPU from the GPUs may be referred to as backwardpropagation.

Once the workload (422) is executed, the computing system may generate aworkload output and provide the workload output to a user. The workloadoutput may include workload data processed by cascading data between atleast three GPUs.

For further explanation, FIG. 5 sets forth a flow chart illustrating afurther exemplary method for reconfiguring processing groups forcascading data workloads according to embodiments of the presentinvention that includes receiving (402) a request (420) to reconfigure acomputing system to execute a workload (422), wherein the computingsystem comprises a first processing group and a second processing group,wherein the first processing group comprises a first central processingunit (CPU), a first graphics processing unit (GPU), and a second GPU,and wherein the second processing group comprises a second CPU and athird GPU; reconfiguring (404) the computing system includingdeactivating a processor link between the first CPU and the second GPU,deactivating a processor link between the second CPU and the third GPU,and activating a processor link spanning the first processor group andthe second processor group between the second GPU and the third GPU; andexecuting (406) the workload (422) using the first GPU, second GPU, andthird GPU including cascading data, via processor links, from the firstCPU to the first GPU, from the first GPU to the second GPU, and from thesecond GPU to the third GPU.

The method of FIG. 5 differs from the method of FIG. 4, however, in thatreconfiguring (404) the computing system including deactivating aprocessor link between the first CPU and the second GPU, deactivating aprocessor link between the second CPU and the third GPU, and activatinga processor link spanning the first processor group and the secondprocessor group between the second GPU and the third GPU includessending (502) a signal to a bus multiplexer to deactivate the processorlink between the first CPU and the second GPU, deactivate the processorlink between the second CPU and the third GPU, and activate a processorlink spanning the first processor group and the second processor groupbetween the second GPU and the third GPU.

Sending (502) a signal to a bus multiplexer to deactivate the processorlink between the first CPU and the second GPU, deactivate the processorlink between the second CPU and the third GPU, and activate a processorlink spanning the first processor group and the second processor groupbetween the second GPU and the third GPU may be carried out by areconfiguration module sending the signal to one or more busmultiplexers. In response, the bus multiplexer may select and deselectsignals on the processor link causing one or more processor linksbetween a CPU and GPU or between two GPUs to become active or inactive.

For further explanation, FIG. 6 sets forth a flow chart illustrating afurther exemplary method for reconfiguring processing groups forcascading data workloads according to embodiments of the presentinvention that includes receiving (402) a request (420) to reconfigure acomputing system to execute a workload (422), wherein the computingsystem comprises a first processing group and a second processing group,wherein the first processing group comprises a first central processingunit (CPU), a first graphics processing unit (GPU), and a second GPU,and wherein the second processing group comprises a second CPU and athird GPU; reconfiguring (404) the computing system includingdeactivating a processor link between the first CPU and the second GPU,deactivating a processor link between the second CPU and the third GPU,and activating a processor link spanning the first processor group andthe second processor group between the second GPU and the third GPU; andexecuting (406) the workload (422) using the first GPU, second GPU, andthird GPU including cascading data, via processor links, from the firstCPU to the first GPU, from the first GPU to the second GPU, and from thesecond GPU to the third GPU.

The method of FIG. 6 differs from the method of FIG. 4, however, in thatexecuting (406) the workload (422) using the first GPU, second GPU, andthird GPU including cascading data, via processor links, from the firstCPU to the first GPU, from the first GPU to the second GPU, and from thesecond GPU to the third GPU includes cascading (602) data, via processorlinks, from the third GPU to the fourth GPU. Cascading (602) data, viaprocessor links, from the third GPU to the fourth GPU may be carried outby sending processed data directly from the third GPU on the secondprocessing group to the fourth GPU on the second processing group usingthe processor link between the third GPU and the fourth GPU. The datacascaded from the third GPU to the fourth GPU may be processed datareceived from the second GPU on the first processing group. The forthGPU may be coupled to the second CPU via a processor link.

For further explanation, FIG. 7 sets forth a flow chart illustrating afurther exemplary method for reconfiguring processing groups forcascading data workloads according to embodiments of the presentinvention that includes receiving (402) a request (420) to reconfigure acomputing system to execute a workload (422), wherein the computingsystem comprises a first processing group and a second processing group,wherein the first processing group comprises a first central processingunit (CPU), a first graphics processing unit (GPU), and a second GPU,and wherein the second processing group comprises a second CPU and athird GPU; reconfiguring (404) the computing system includingdeactivating a processor link between the first CPU and the second GPU,deactivating a processor link between the second CPU and the third GPU,and activating a processor link spanning the first processor group andthe second processor group between the second GPU and the third GPU; andexecuting (406) the workload (422) using the first GPU, second GPU, andthird GPU including cascading data, via processor links, from the firstCPU to the first GPU, from the first GPU to the second GPU, and from thesecond GPU to the third GPU.

The method of FIG. 7 differs from the method of FIG. 4, however, in thatreconfiguring (404) the computing system including deactivating aprocessor link between the first CPU and the second GPU, deactivating aprocessor link between the second CPU and the third GPU, and activatinga processor link spanning the first processor group and the secondprocessor group between the second GPU and the third GPU includesdirectly connecting (702) the second GPU on the first processing groupto the third GPU on the second processing group via a processor linkbetween the second GPU and the third GPU.

Directly connecting (702) the second GPU on the first processing groupto the third GPU on the second processing group via a processor linkbetween the second GPU and the third GPU may be carried out by signalinga bus multiplexer to activate the processor link between the second GPUand the third GPU spanning the first processing group and the secondprocessing group. The processor link may be directly connecting thesecond GPU and the third GPU in that there exists no intermediary switchor other computing element between the second GPU and the third GPU.

In view of the explanations set forth above, readers will recognize thatthe benefits of reconfiguring processing groups for cascading dataworkloads according to embodiments of the present invention include:

-   -   Improving the operation of a computing system by allowing        reconfiguration based on the characteristics of different        workloads, increasing computing system efficiency.    -   Improving the operation of a computing system by reconfiguring a        computing system for workloads that benefit from multiple GPUs        capable of cascading data between them, increasing computing        system functionality and efficiency.

Exemplary embodiments of the present invention are described largely inthe context of a fully functional computer system for reconfiguringprocessing groups for cascading data workloads. Readers of skill in theart will recognize, however, that the present invention also may beembodied in a computer program product disposed upon computer readablestorage media for use with any suitable data processing system. Suchcomputer readable storage media may be any storage medium formachine-readable information, including magnetic media, optical media,or other suitable media. Examples of such media include magnetic disksin hard drives or diskettes, compact disks for optical drives, magnetictape, and others as will occur to those of skill in the art. Personsskilled in the art will immediately recognize that any computer systemhaving suitable programming means will be capable of executing the stepsof the method of the invention as embodied in a computer programproduct. Persons skilled in the art will recognize also that, althoughsome of the exemplary embodiments described in this specification areoriented to software installed and executing on computer hardware,nevertheless, alternative embodiments implemented as firmware or ashardware are well within the scope of the present invention.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

It will be understood from the foregoing description that modificationsand changes may be made in various embodiments of the present inventionwithout departing from its true spirit. The descriptions in thisspecification are for purposes of illustration only and are not to beconstrued in a limiting sense. The scope of the present invention islimited only by the language of the following claims.

What is claimed is:
 1. A method of reconfiguring processing groups forcascading data workloads, the method comprising: receiving a request toreconfigure a computing system to execute a workload, wherein thecomputing system comprises a first processing group and a secondprocessing group, wherein the first processing group comprises a firstcentral processing unit (CPU), a first graphics processing unit (GPU),and a second GPU, and wherein the second processing group comprises asecond CPU and a third GPU; reconfiguring the computing system includingdeactivating a processor link between the first CPU and the second GPU,deactivating a processor link between the second CPU and the third GPU,and activating a processor link spanning the first processor group andthe second processor group between the second GPU and the third GPU; andexecuting the workload using the first GPU, second GPU, and third GPUincluding cascading data, via processor links, from the first CPU to thefirst GPU, from the first GPU to the second GPU, and from the second GPUto the third GPU.
 2. The method of claim 1, wherein reconfiguring thecomputing system comprises sending a signal to a bus multiplexer todeactivate the processor link between the first CPU and the second GPU,deactivate the processor link between the second CPU and the third GPU,and activate a processor link spanning the first processor group and thesecond processor group between the second GPU and the third GPU.
 3. Themethod of claim 1, wherein the second processing group further comprisesa fourth GPU coupled to the third GPU via a processor link, and whereinexecuting the workload using the first GPU, second GPU, and third GPUcomprises cascading data, via processor links, from the third GPU to thefourth GPU.
 4. The method of claim 1, wherein reconfiguring thecomputing system comprises directly connecting the second GPU on thefirst processing group to the third GPU on the second processing groupvia a processor link between the second GPU and the third GPU.
 5. Themethod of claim 1, wherein the computing system is reconfigured based onthe characteristics of the workload.
 6. The method of claim 1, whereinreconfiguring the computing system is performed at boot time.
 7. Themethod of claim 1, wherein the first CPU in the first processing groupis coupled to the second CPU in the second processing group via anintergroup bus fabric.
 8. An apparatus for reconfiguring processinggroups for cascading data workloads, the apparatus comprising a computerprocessor, a computer memory operatively coupled to the computerprocessor, the computer memory having disposed within it computerprogram instructions that, when executed by the computer processor,cause the apparatus to carry out the steps of: receiving a request toreconfigure a computing system to execute a workload, wherein thecomputing system comprises a first processing group and a secondprocessing group, wherein the first processing group comprises a firstcentral processing unit (CPU), a first graphics processing unit (GPU),and a second GPU, and wherein the second processing group comprises asecond CPU and a third GPU; reconfiguring the computing system includingdeactivating a processor link between the first CPU and the second GPU,deactivating a processor link between the second CPU and the third GPU,and activating a processor link spanning the first processor group andthe second processor group between the second GPU and the third GPU; andexecuting the workload using the first GPU, second GPU, and third GPUincluding cascading data, via processor links, from the first CPU to thefirst GPU, from the first GPU to the second GPU, and from the second GPUto the third GPU.
 9. The apparatus of claim 8, wherein reconfiguring thecomputing system comprises sending a signal to a bus multiplexer todeactivate the processor link between the first CPU and the second GPU,deactivate the processor link between the second CPU and the third GPU,and activate a processor link spanning the first processor group and thesecond processor group between the second GPU and the third GPU.
 10. Theapparatus of claim 8, wherein the second processing group furthercomprises a fourth GPU coupled to the third GPU via a processor link,and wherein executing the workload using the first GPU, second GPU, andthird GPU comprises cascading data, via processor links, from the thirdGPU to the fourth GPU.
 11. The apparatus of claim 8, whereinreconfiguring the computing system comprises directly connecting thesecond GPU on the first processing group to the third GPU on the secondprocessing group via a processor link between the second GPU and thethird GPU.
 12. The apparatus of claim 8, wherein the computing system isreconfigured based on the characteristics of the workload.
 13. Theapparatus of claim 8, wherein reconfiguring the computing system isperformed at boot time.
 14. The apparatus of claim 8, wherein the firstCPU in the first processing group is coupled to the second CPU in thesecond processing group via an intergroup bus fabric.
 15. A computerprogram product for reconfiguring processing groups for cascading dataworkloads, the computer program product disposed upon a computerreadable medium, the computer program product comprising computerprogram instructions that, when executed, cause a computer to carry outthe steps of: receiving a request to reconfigure a computing system toexecute a workload, wherein the computing system comprises a firstprocessing group and a second processing group, wherein the firstprocessing group comprises a first central processing unit (CPU), afirst graphics processing unit (GPU), and a second GPU, and wherein thesecond processing group comprises a second CPU and a third GPU;reconfiguring the computing system including deactivating a processorlink between the first CPU and the second GPU, deactivating a processorlink between the second CPU and the third GPU, and activating aprocessor link spanning the first processor group and the secondprocessor group between the second GPU and the third GPU; and executingthe workload using the first GPU, second GPU, and third GPU includingcascading data, via processor links, from the first CPU to the firstGPU, from the first GPU to the second GPU, and from the second GPU tothe third GPU.
 16. The computer program product of claim 15, whereinreconfiguring the computing system comprises sending a signal to a busmultiplexer to deactivate the processor link between the first CPU andthe second GPU, deactivate the processor link between the second CPU andthe third GPU, and activate a processor link spanning the firstprocessor group and the second processor group between the second GPUand the third GPU.
 17. The computer program product of claim 15, whereinthe second processing group further comprises a fourth GPU coupled tothe third GPU via a processor link, and wherein executing the workloadusing the first GPU, second GPU, and third GPU comprises cascading data,via processor links, from the third GPU to the fourth GPU.
 18. Thecomputer program product of claim 15, wherein reconfiguring thecomputing system comprises directly connecting the second GPU on thefirst processing group to the third GPU on the second processing groupvia a processor link between the second GPU and the third GPU.
 19. Thecomputer program product of claim 15, wherein the computing system isreconfigured based on the characteristics of the workload.
 20. Thecomputer program product of claim 15, wherein reconfiguring thecomputing system is performed at boot time.